// SzfObject.cs

using System;
using System.Collections.Generic;
using System.Reflection;

namespace SessionZero.Data;

/// <summary>
/// Represents common metadata for all SzfObjects.
/// </summary>
public class SzfMetadata
{
    public string Name { get; set; } = string.Empty;
    public Version? Version { get; set; }
    public Guid Guid { get; set; }
    public string? Description { get; set; }
    public string? Author { get; set; }
}

public abstract class SzfObject
{
    /// <summary>
    /// The unique string identifier for this SzfObject type, derived from its SzfObjectAttribute.
    /// </summary>
    public string TypeIdentifier { get; }

    /// <summary>
    /// Common metadata for all SzfObjects.
    /// </summary>
    public SzfMetadata Metadata { get; set; } = new SzfMetadata();

    /// <summary>
    /// Default constructor that reads the TypeIdentifier from the SzfObjectAttribute.
    /// </summary>
    protected SzfObject()
    {
        // Read the SzfObjectAttribute from the concrete class type
        var attribute = GetType().GetCustomAttribute<SzfObjectAttribute>();
        if (attribute == null)
        {
            // This indicates a missing attribute, which means the class is not properly defined as an SzfObject.
            throw new InvalidOperationException(
                $"SzfObject class '{GetType().Name}' is missing the SzfObjectAttribute. All concrete SzfObject types must have this attribute.");
        }

        TypeIdentifier = attribute.TypeIdentifier;

        // Initialize metadata with a new GUID, this is a default, can be overridden by parsing
        Metadata.Guid = Guid.NewGuid();
    }

    /// <summary>
    /// Populates the object's metadata from a dictionary of parsed SzfFields.
    /// This method is intended to be overridden by derived classes to handle their specific metadata.
    /// </summary>
    /// <param name="metadata">A dictionary of metadata fields.</param>
    public virtual void PopulateFromMetadata(Dictionary<string, SzfField> metadata)
    {
        if (metadata.TryGetValue("Name", out var nameField))
            Metadata.Name = nameField.Value?.ToString() ?? string.Empty;

        if (metadata.TryGetValue("Version", out var versionField))
        {
            if (Version.TryParse(versionField.Value?.ToString(), out var ver))
            {
                Metadata.Version = ver;
            }
        }

        if (metadata.TryGetValue("GUID", out var guidField))
        {
            if (Guid.TryParse(guidField.Value?.ToString() ?? string.Empty, out var guid))
            {
                Metadata.Guid = guid;
            }
        }

        if (metadata.TryGetValue("Description", out var descriptionField))
            Metadata.Description = descriptionField.Value?.ToString();

        if (metadata.TryGetValue("Author", out var authorField))
            Metadata.Author = authorField.Value?.ToString();
    }

    /// <summary>
    /// Parses the sections of the Szf object from a flat list of SzfSection objects
    /// and constructs the object's internal data structure. This is an abstract method
    /// that must be implemented by derived classes.
    /// </summary>
    /// <param name="sections">A list of parsed SzfSections.</param>
    public abstract void ParseSections(List<SzfSection> sections);

    /// <summary>
    /// Generates the metadata section of the Szf file using the provided writer.
    /// This method is virtual and can be extended by derived classes to add their specific metadata.
    /// </summary>
    /// <param name="writer">The SzfFieldWriter to use for writing.</param>
    public virtual void GenerateMetadata(SzfFieldWriter writer)
    {
        // Write standard metadata fields common to all SzfObjects
        writer.AppendSectionHeader("Metadata"); // Corrected method call
        writer.WriteField("Name", "text", Metadata.Name);
        writer.WriteField("Version", "text",
            Metadata.Version?.ToString() ?? string.Empty); // Ensure Version is not null
        writer.WriteField("GUID", "text", Metadata.Guid.ToString());

        if (!string.IsNullOrEmpty(Metadata.Description))
            writer.WriteField("Description", "text-field", Metadata.Description);
        if (!string.IsNullOrEmpty(Metadata.Author))
            writer.WriteField("Author", "text", Metadata.Author);

        writer.AppendLine(); // Corrected method call to end section with a newline
    }

    /// <summary>
    /// Generates the content sections of the Szf file using the provided writer.
    /// This is an abstract method that must be implemented by derived classes.
    /// </summary>
    /// <param name="writer">The SzfFieldWriter to use for writing.</param>
    public abstract void GenerateContent(SzfFieldWriter writer);

    /// <summary>
    /// Validates the current state of the Szf object.
    /// This method is virtual and can be extended by derived classes to add their specific validation rules.
    /// </summary>
    /// <returns>A SzfValidationResult indicating any errors or warnings.</returns>
    public virtual SzfValidationResult Validate()
    {
        var result = new SzfValidationResult();

        if (string.IsNullOrWhiteSpace(Metadata.Name))
            result.AddError("Name is required for SzfObject");
        if (Metadata.Version == null)
            result.AddError("Version is required for SzfObject");
        if (Metadata.Guid == Guid.Empty)
            result.AddError("GUID is required for SzfObject");

        return result;
    }
}

public class SzfValidationResult
{
    public bool IsValid { get; set; } = true;
    public List<string> Errors { get; set; } = [];
    public List<string> Warnings { get; set; } = [];

    public void AddError(string error)
    {
        Errors.Add(error);
        IsValid = false;
    }

    public void AddWarning(string warning)
    {
        Warnings.Add(warning);
    }
}

public class SzfField
{
    public string Name { get; set; } = string.Empty;
    public string Type { get; set; } = string.Empty;
    public object? Value { get; set; }
}